Tag Archives: parasitoids

465-470 I. H. Williams
Integrating parasitoids into management of pollen beetle onoilseed rape
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Integrating parasitoids into management of pollen beetle onoilseed rape

I. H. Williams

Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ,UK

Abstract:

Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ,UK Hymenopterous parasitoids can exert substantial natural control on oilseed rape pest populations. This paper reviews recent work at Rothamsted Research on integrating parasitoids into the management of rape pests. It focuses on the pollen beetle, Meligethes aeneus, and its two larval endoparasitoids, Phradis interstitialis and Tersilochus heterocerus. Strategic research on the behavioural ecology of the parasitoids is described. Phradis interstitialis was shown to use upwind anemotaxis to locate the crop. Within-field spatio-temporal distributions of M. aeneus adults and larvae were complex with irregular patterns of aggregation. Whereas P. interstitialis was closely associated temporally and spatially with the distribution of its host, T. heterocerus larvae were as abundant outside dense host patches as within them and showed little pattern. Both parasitoid species overwinter in the soil of the rape field and emerge the following spring. Post-harvest soil cultivations, particularly ploughing, can reduce their survival, whereas non-inversion tillage is less harmful. Phenological studies show that pyrethroid applications during flowering threaten parasitoid populations. Implications of the research for conservation biological control and the development of more environmentally-friendly crop protection is discussed.

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187-190 L. Hanni and A. Luik
Parasitism of raspberry beetle (Byturus tomentosus F.) larvae in different cropping techniques of red raspberry
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Parasitism of raspberry beetle (Byturus tomentosus F.) larvae in different cropping techniques of red raspberry

L. Hanni¹ and A. Luik²

¹Polli Horticultural Research Centre, Institute of Agricultural and Environmental Sciences,Estonian University of Life Sciences, Viljandi county, Karksi–Nuia, Polli, 69104, Estonia;e-mail: liina.hanni@emu.ee
²Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences,Kreutzwaldi St. 64, 51014, Tartu, Estonia

Abstract:

Raspberry beetle (Byturus tomentosus F.) is the major pest in raspberry in Estonia and throughout Europe. The parasitism rate of raspberry beetle larvae was studied in different cropping systems and in wild raspberry. In the raspberry plantation two intercropping systems were used: intercropping with 7 herbs and with black currant. The control variant was monocropping. Larvae from wild raspberries were collected from a clear cut area in the neighbourhood of the plantation. In the monocropping area the larval parasitism rate was less than 5%. The intercropping of raspberries with herbs increased the larval parasitism rate (9.4%), while in the intercropping with black currant, it decreased (2.2%). Larvae from wild raspberry were the most parasitized (26.1%). Further investigation is needed to explain species composition of parasitoids in raspberry beetle larvae.

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227-230 R. Kevväi, E. Veromann, A. Luik and M. Saarniit
Cabbage seed weevil (Ceutorhynchus assimilis Payk.) and its parasitoids in oilseed rape crops in Estonia
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Cabbage seed weevil (Ceutorhynchus assimilis Payk.) and its parasitoids in oilseed rape crops in Estonia

R. Kevväi, E. Veromann, A. Luik and M. Saarniit

Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences,Kreutzwaldi St. 64, EE51014, Tartu, Estonia; e-mail: reelika.kevvai@emu.ee

Abstract:

Abstract: Besides pollen beetles, the cabbage seed weevil is the second most numerous crucifer-specialist in Estonian oilseed rape crops. The occurrence of cabbage seed weevil and its hymenopterous parasitoids was studied in standard and integrated cropping systems in winter and spring oilseed rape crops in 2004–2005. Cabbage seed weevil is more synchronized with winter oilseed rape and its abundance was greater in winter than in spring. The average pod damage was 9.9% in winter and only 1.2% in the spring crop. In winter oilseed rape, the population of C. assimilis was more numerous in the integrated than in the standard cropping system. Three parasitoids of seed weevil – Trichomalus perfectus, Stenomalina gracilis, Mesopolobus morys – were caught with yellow water traps but their abundance was low. The larval parasitism rate was higher in the integrated cropping system (22.2%) than in the standard cropping system (9.7%). Trichomalus perfectus was the dominant species emerging from C. assimilis larvae.

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